Magnesia-carbon brick is made of high melting point basic oxide magnesium oxide (melting point 2800℃) and high melting point carbon material which is difficult to be penetrated by slag as raw materials, and various non-oxide additives are added. A non-burning carbon composite refractory combined with a carbonaceous binder. Magnesia carbon brick is mainly used in the lining of converter, AC electric arc furnace, DC electric arc furnace, ladle slag line and other parts.

As a kind of composite refractory material, magnesia carbon brick effectively utilizes the strong slag resistance of magnesia and the high thermal conductivity and low expansion of carbon to compensate for the poor spalling resistance of magnesia. Its main characteristics are: good high temperature resistance, strong slag resistance, good thermal shock resistance, low high temperature creep. Conventional magnesia-carbon bricks made with synthetic tar bonds according to the cold mixing process harden and gain the necessary strength during tar damage, thus forming an isotropic glassy carbon. This carbon does not show thermoplasticity, which can timely eliminate a large amount of stress during lining baking or operation. The magnesia carbon brick produced with asphalt binder has high high temperature plasticity due to the anisotropic graphitized coke structure formed in the process of asphalt carbonization.

Magnesia is the main raw material for the production of MGO-C bricks, which can be divided into fused magnesia and sintered magnesia. Compared with sintered magnesia, fused magnesia has the advantages of coarse crystal grains and high particle volume density, and is the main raw material used in the production of magnesia carbon bricks. The production of ordinary magnesia refractories requires magnesia raw materials mainly to have high temperature strength and corrosion resistance, so attention is paid to the purity of magnesia and the C/S ratio and B2O3 content in the chemical composition. With the development of metallurgical industry, smelting conditions are increasingly harsh, in metallurgical equipment (converter, electric furnace, ladle, etc.) on the application of MGO-C brick used magnesia, in addition to chemical composition, in terms of organizational structure, but also require high density and large crystallization.

With the progress of smelting technology to the new requirements of refractory materials, the traditional magnesia carbon brick in the long-term application practice process found the following problems: (1) due to the high thermal conductivity to increase the heat loss, the steel temperature increases, resulting in increased energy consumption, while increasing the erosion of refractory materials and a series of problems; As a special refining furnace lining material, such as smelting high-quality clean steel and ultra-low carbon steel in VOD refining ladle, it will cause carburization problems; ③ Consume a lot of valuable graphite resources. In view of the above situation, in recent years, the development of low carbon magnesium carbon brick for refining ladle with low carbon content and excellent performance has received attention from domestic and foreign industry.

The main problems caused by the decrease of carbon content in magnesia-carbon brick are the decrease of thermal shock stability and slag permeability resistance. As we all know, after the carbon content of magnesium-carbon brick is reduced, the thermal conductivity of the brick is decreased, the elastic modulus is increased, and the thermal shock resistance stability of the brick is deteriorated. With the decrease of carbon content, the wettability of slag, molten steel and the material is enhanced, and the permeability resistance of the material to molten slag and molten steel is deteriorated.

The understanding of solving these problems mainly includes the following three aspects: (1) Improving the thermal shock stability of magnesium-carbon brick by improving the carbon structure of bonded carbon: The traditional magnesia carbon brick binder is mostly phenolic resin, the carbonized carbon structure is isotropic glassy, so the magnesia carbon brick is brittle, the elastic modulus is high, the thermal stability of the product is bad, and the high temperature strength of the product is low. After introducing graphitized carbon precursor into phenolic resin, the composite binder can carbonize into secondary carbon with flow or Mosaic structure, or form nano-carbon fiber in situ. The thermal shock stability and high temperature strength of low-carbon magnesia carbon brick can be improved by improving the carbon structure and enhancing the formation of nano-carbon fiber. ② Optimize the matrix structure of magnesia-carbon brick: the thermal shock stability and slag permeability resistance of magnesia-carbon brick mainly depend on the composition and structure of the matrix, in the case of a significant reduction in carbon content, how to improve the contact frequency of aggregate particles and carbon particles, that is, reduce the size of carbon particles and ensure its high dispersion, is one of the important measures to improve the thermal shock stability and slag permeability resistance of low-carbon magnesia-carbon brick. The size, shape and distribution of pores can be controlled by adjusting the particle size composition of the substrate, which also has obvious influence on the thermal conductivity of the material. ③ The use of high-efficiency antioxidants: with the reduction of carbon content in magnesia-carbon bricks, the oxidation protection of carbon is particularly important, so the use of appropriate high-efficiency antioxidants is also very necessary.